Weld made her acting debut on television at age 12 and her feature film debut the same year in a bit role in the 1956 Alfred Hitchcock crime drama, The Wrong Man. The pressures of her career, however, resulted in a nervous breakdown at age nine, alcoholism by age 12, and a suicide attempt around the same time. In 1956, Weld played the lead in Rock, Rock, Rock, which featured record promoter Alan Freed and singers Chuck Berry, Frankie Lymon, and Johnny Burnette. In the film, Connie Francis performed the vocals for Weld's singing parts. In 1959, having appeared as "Dorothy" in The Five Pennies, she was cast as Thalia Menninger in the CBS television series The Many Loves of Dobie Gillis. Although Weld was a cast member for only a single season, the show gave her considerable national publicity, and she was named a co-winner of a "Most Promising Newcomer" award at the Golden Globe Awards.
She was put under contract to Twentieth Century-Fox and appeared in feature films and episdodes of Fox-produced TV series. In 1960, she appeared as Joy, a free-spirited university student in High Time, starring Bing Crosby and Fabian. She also guest-starred that season on NBC's The Tab Hunter Show. On November 12, 1961, she played a young singer, Cherie, in the seventh episode of ABC's television series Bus Stop, with Marilyn Maxwell and Gary Lockwood. This was the same role Marilyn Monroe had played in the 1956 film Bus Stop, based on William Inge's play. Kim Stanley played Cherie on Broadway.
Weld's mother was scandalized by her teenage daughter's affairs with older men, such as actor John Ireland, but Weld resisted, saying, "'If you don’t leave me alone, I’ll quit being an actress — which means there ain’t gonna be no more money for you, Mama.' In 1961, when Weld was 18, she had an off-screen romance with Elvis Presley, her costar in Wild in the Country.
She was well received for her portrayal of an abuse victim in Return to Peyton Place, the sequel to the 1956 film Peyton Place, but the film was less successful than its predecessor. Weld appeared with Jackie Gleason and Steve McQueen in the 1963 comedy Soldier in the Rain; her performance was well received, but the film was only a minor success. That same year she and former co-star Dwayne Hickman appeared in Jack Palance's circus drama, The Greatest Show on Earth on ABC, but in separate episodes. Later in her career, she turned down roles in films that became great successes, such as Bonnie and Clyde, Rosemary's Baby, True Grit, and Bob & Carol & Ted & Alice.
In her thirties, Weld performed in Looking for Mr. Goodbar (1977), for which she was nominated for an Academy Award for Best Supporting Actress; Who'll Stop the Rain (1978) opposite Nick Nolte; and Michael Mann's acclaimed 1981 film Thief, opposite James Caan. In 1984, she appeared in Sergio Leone's gangster epic Once Upon a Time in America, playing a jeweler's secretary who is in on a plan to steal a shipment of diamonds. While the robbery is happening she goads Robert De Niro's character, David "Noodles" Aaronson, into "raping" her with her complicity.
Weld has also appeared in a number of television movies, including a remake of the much-filmed tearjerker Madame X (1981), Circle of Violence (1986), Reflections of Murder (1974) (an American remake of the French film Les Diaboliques), and A Question of Guilt, in which she plays a woman accused of murdering her children. In 1993, she played a police officer's neurotic wife in Falling Down, starring Michael Douglas and Robert Duvall.
Weld and her demanding stage mother were definitively on the outs in the mid 1980s, and she began telling people that her mother was dead even though she was still alive. “I hated Mama,” Weld told The New York Times. “She took my childhood away from me. I was expected to make up for everything that had gone wrong with Mama’s life. She became obsessed with me, pouring out all her pent-up love—alleged love—on me. It’s been heavy on my shoulders ever since. I didn’t feel really free until she died. Otherwise her death didn’t really affect me much.” Tuesday’s mother retorted to the press, “I didn’t like being called dead." In reality Tuesday's mom was very much alive. (She did pass away in 2001 at the age of 90).
Weld was married to conductor Pinchas Zuckerman from 1985 to 1998. When he divorced her, Zuckerman complained that she had stopped caring about his career: “Why do I have to go to another concert when I’ve heard the piece before?” she would ask him. In Ethan Hawke’s dorm-roomy Chelsea Walls (2001), Weld’s unpredictability has gone to such an extreme that there’s almost a total disconnection between her oddball reactions and what Hawke has given her to say. Since 2001, Weld has lived quietly in Aspen, Colorado, and not much has been heard from her, but she knows full well that silence is much more intriguing than any further work might be. Since the ‘70s, she’s been rumored to have occult interests and connections, but her main project has always been her own ravenous mind, and at this point she just wants to be alone with it. “I like to be alone in general,” she once said. “I have a hunger for it. I eat up silence".
It is reported that Weld suffers from bipolar disorder, and as she turns 70 she is being cared for by her daughter. However, that report has not been fully proven or disproven. In recent years she has been scheduled to appear at movie fan shows and film festivals, but often she will cancel the appearance at the last minute. Despite having the demanding stage mother, Weld resisted the fame and still does late in her life. Even though she is not seen much these days, hopefully she is at peace with her life and knows how many fans she still has...